Travel booking site Airbnb says mobile adoption of its service is “exploding”, and it’s marking a new milestone today to prove its point – over a quarter of its traffic now comes from mobile devices.

Half of those visits come from Apple’s iPhone and iPad and the iPhone app alone has been downloaded more than a million times. A sizable portion of those users still seem to be active on the app, as 500,000 of them upgraded to Airbnb’s latest version when it went live earlier this month.

Though room bookings and mobile might not always seem to go together, Airbnb believes it’s an improved experience. In the company’s own words:

As mobile becomes customers’ preferred medium for connecting online, we’ve seen a shift in user behavior that indicates mobile will be increasingly important for businesses outside of the technology industry. Specifically, we’re seeing explosive growth in mobile adoption, which is driving real value to our travel business and contributing to a better experience for our community.

Airbnb maintains that the uptake of mobile is contributing a better user experience for both hosts and guests. At the least, they’re communicating more, as over 530,000 messages were sent on Airbnb’s mobile platform last month. They’re also saving some time. The company also says that reservations happen faster on mobile and messages get responded to as much as three times faster than on the Web.